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The Green Machine

Jasper Hill Farm Integrated Biological Waste Treatment and Energy/Nutrient Recovery System

green machine & barn from north hillside

(All photos by Bob M. Montgomery Images)


  • Summary
  • Background and Objectives
  • Design Build Team and Project Timeline
  • Replicability
  • Waste Flow
  • Composting & Energy Recovery
  • Anaerobic Digestion with Methane Capture
  • Advanced Botanical System
  • Land Application
  • The Big Picture
  • More Information & Links

    Jasper Hill Farm has designed and constructed an enclosed, integrated, biological treatment system for managing the manure, whey, and wash-water that result from milking cows and producing cheese. This three-component system employs Aerated Composting for manure solids, Anaerobic Digestion (AD) for phase one of liquids treatment, and an Advanced Botanical System (ABS) for phase two of liquids treatment. Finished compost will be spread on pastures as a soil amendment. Treated water from the ABS will irrigate pastures and extend the grazing season. The integrated design recovers heat energy from the compost to heat the liquid wastes and methane gas from the (AD) tanks used to replace conventional fuel-oil used in our creamery boiler.

    process diagram_4-12-11


    Jasper Hill Farm was started by brothers Mateo and Andy Kehler in 2003. The farm is located in Greensboro, VT, a rural community of 700 residents, and is a typical Vermont ‘hill’ farm, comprised of approx 100 open acres and 160 acres of mixed woodland. Jasper Hill Farm’s award winning cheeses are made from the milk of its herd of 45 registered Ayrshire milking cows. The farm employs an intensive rotational grazing system, feeds dry (unfermented) feed and produces the cleanest milk in the state of Vermont. Jasper Hill Farm produces approximately 100,000 lbs of cheese per year, and employs 8 full time workers

    Adept at managing biological systems, Jasper Hill Farm envisioned a ‘whole system’ approach to nutrient management, wastewater and energy challenges on the farm. An integrated approach will extend Jasper Hill’s success upstream to raw product production/processing and downstream to waste management and nutrient/energy recovery, and will demonstrate sustainable practices and technologies for Vermont’s working landscapes and environment.

    Design and construction costs for the Green Machine were made possible in part by grant funding from:

    United States Department of Agriculture Environmental Quality Incentives Program (USDA EQIP)

    National Resource Conservation Service Alternative Manure Management Program (NRCS-AMM)

    Vermont Agency of Agriculture Food & Markets BMP Program

    Vermont NCIC


    Andy & Mateo Kehler – Jasper Hill Farm

    James Coe – Jasper Hill Farm

    Highfields Center for Composting


    EOS Research

    Mountain Air Systems


    Project Visioning: 2009

    Schematic Design: 2010 - 2011

    Funding: 2010 - 2011

    Construction: July 2011 – August 2012

    Substantial Completion: August 2012

    Start-up: August 2012 – December 2012

    Field Application / Nutrient Management Plan: Spring 2012


    This innovative project integrates multiple waste treatment, nutrient management, and energy recovery strategies into a single “closed loop” system that is scaled to the dairy it serves. Replicability is anticipated in part or in whole and Jasper Hill Farm is committed to facilitating the dissemination of the technical design, measured outcomes, and lessons learned throughout the project.

    For specific information and design questions, contact us at This e-mail address is being protected from spambots. You need JavaScript enabled to view it

    Completed in August 2012, the “Green Machine” is now up and running.


    A traditional tie-barn gutter cleaner removes manure and sawdust bedding from our 50 head cow barn and deposits it into a hopper on top of a Separator.

    The screw press separator extracts the liquid manure and mixes it with our cheese house whey and wash-water in a 2,000 gallon pump-station. The separated solids are stacked for transfer to our Static pile aerated composting shed. The combined liquids are ready for transfer to the Anaerobic Digester.

    separator & pile

    Vincent KP-10 separator


    The manure solids are transferred to a static-pile composting bay where they will cure for the next 60 days.

    The compost bay

    The covered compost shed has aeration channels cast in the floor slab to extract thermal energy from the bottom of the pile while pulling in fresh oxygen to the pile from the top. The piles do not need turning like traditional composting and the aeration is managed to maximize thermal capture and pile break down. The compost shed is divided into 7 aeration zones. A zone will typically climb in temperature for approximately 40 minutes or until it plateaus at 150 degrees F. At this time a knife valve opens introducing vacuum to the base of the pile and Heat energy is extracted for approximately 20 minutes or until the pile cools to 100 degrees. This aeration cycle is staggered and repeated across the 7 aeration zones to maintain a constant 150 degree heat supply and to consistently re-invigorate the piles with oxygen.

    CJH Green Machine 20120820 - 0012

    A PVC manifold assembly connects the 7 aeration zones and ducts the hot, moisture laden air into an iso-bar heat exchanger developed by Agri-Lab Inc . Inside the heat exchanger, the hot wet compost air condenses against an array of refrigerant charged stainless steel tubes transferring energy to an adjacent 250 gallon water tank. The resulting hot water is circulated through the AD room to heat our (3) 7,000 gallon Anaerobic Digester tanks.

    Ventilation Manifold

    Iso Bar Heat Exchanger


    Mixed liquids (whey, wash water, manure) as well as system leachate and condensate are routed into a small scale anaerobic digester. The digester provides primary wastewater treatment, which settles out much of the suspended solids. This solid mass is broken down by anaerobic bacteria and converted into biogas and soluble biochemical oxygen demand. The biogas is recovered to provide energy needed for heating water in the creamery, while the clarified effluent is pumped to the advanced botanical system for the second stage of treatment.

    the AD room


    Effluent from the anaerobic digester is channeled through a series of anoxic and aerobic tanks, pumps, and monitoring equipment in the adjacent greenhouse. Remaining biochemical oxygen demand, nutrients, and solids continue to be broken down by a robust ecosystem of plants and microflora in distinct treatment zones. All the major groups of life are represented, including microscopic algae, fungi, bacteria; tiny animals called protozoa; upward to snails, clams, fish and zooplankton. Higher plants, including shrubs and trees, are grown on industrial strength fiberglass racks suspended within the system. The result is an efficient and refined wastewater system capable of achieving high quality water without the need for hazardous chemicals.

    The ABS

    Upstairs in the ABS


    Once both solids and liquids have reached levels acceptable under our nutrient management plan, both can be land applied. Liquids will be used to strategically drip irrigate pastures and a developing orchard. Finished compost is field-applied to our grazing pastures in accordance with our nutrient management plan to maintain healthy soil conditions, reduce erosion, and improve crop yields over time. Any excess compost is sold for additional income.


    The implementation of this system has allowed us to better understand the nutrient and energy pathways on our farm, and to harness and repurpose those resources. As a pasture-based dairy farm, the health of our land and cows are integral to the health of the business as a whole. The new facility affords us more control over the elements that assure quality soil, grass, and cows, so that we can continue to produce the best milk possible for our award-winning cheeses .

    The Green Machine and Creamery


    While our farm is not open to the public, you can sign up for tours of the Green Machine through the Center for an Agricultural Economy in Hardwick, VT.

    For more information about our waste management system, design specs or technical questions, write us at This e-mail address is being protected from spambots. You need JavaScript enabled to view it


    United States Department of Agriculture Environmental Quality Incentives Program (USDA EQIP)

    National Resource Conservation Service Alternative Manure Management Program (NRCS-AMM)

    Vermont Agency of Agriculture Food & Markets BMP Program

    Vermont NCIC

    Highfields Center for Composting


    EOS Research

    Mountain Air Systems


    Center for an Agricultural Economy (tours)